Forget 'On Record,' 2014 May Have Been Warmest Year In Last 2,000

Eric Mack
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UPDATE: This post originally ran under the headline suggesting 2014 may have been the warmest year in the past 5,000. I've since spoken directly with the scientist, Don Wuebbles of the University of Illinois, who was quoted to that effect in other publications and he clarified that the data reaching back that far is less certain than data going back 1,7oo to 2,000 years and that he would give much less weight to the 5,000 year claim.

Last week NASA and NOAA released a preliminary analysis claiming that last year was the warmest since record-keeping began in 1880, based on globally averaged temperature data collected from a network of land and water surface sensors. The reaction to the news has been fairly predictable, with some skeptics nit-picking around the margin of error and most climate scientists pointing to 2014' s heat as further evidence of a long-term warming trend, often noting that the ten hottest years on record have all occurred since 1997.

"The global warmth of 2014 is just another reminder that the planet is warming and warming fast. Perhaps most remarkable is that this level of warmth was achieved without the expected large El Niño," said Jonathan Overpeck, co-director of Arizona State University's Institute of the Environment and one of 21 climate scientists polled about the new report by the Washington Post. "2014 was one for the record books in many ways, and it serves as a great illustration of what global warming is all about."

While most scientists acknowledge that a single record-breaking year is actually less significant than it may seem to the layman because longer-term trends are more important when talking about climate, a minority of researchers say the real story is that warming patterns have not kept pace with what was predicted in earlier models.

"With 2014 essentially tied with 2005 and 2010 for hottest year, this implies that there has been essentially no trend in warming over the past decade. This ‘almost’ record year does not help the growing discrepancy between the climate model projections and the surface temperature observations," said Judith Curry, a professor at the Georgia Institute of Technology.

But the majority of reactions, at least from those in the climate science community who don't mind talking to the press, is pretty clear: The world has continued to warm, not just last year, but over the long-term.

Assessing the really long-term isn't that easy when records only go back 134 years, but Don Wuebbles of the University of Illinois, a contributor to multiple International Panel on Climate Change reports, doesn't shy away from assessments that reach back much further into the past.

"We can safely say it’s probably the warmest year in 1,700 and 2,000 years," he told me on Sunday over the phone, explaining that researchers use proxies for temperature to make such determinations, including a combination of analyses taken from tree rings, ice cores, soils and other sources. Wuebbles also explained more about the historic climate record in the TEDx talk below from 2011.